From: Sergey Senozhatsky Date: Thu, 9 Oct 2014 22:29:57 +0000 (-0700) Subject: zram: use notify_free to account all free notifications X-Git-Tag: firefly_0821_release~3680^2~8^2^2~10 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c85f1d31057bdde75716b19e6456a91c5c2273da;p=firefly-linux-kernel-4.4.55.git zram: use notify_free to account all free notifications `notify_free' device attribute accounts the number of slot free notifications and internally represents the number of zram_free_page() calls. Slot free notifications are sent only when device is used as a swap device, hence `notify_free' is used only for swap devices. Since f4659d8e620d08 (zram: support REQ_DISCARD) ZRAM handles yet another one free notification (also via zram_free_page() call) -- REQ_DISCARD requests, which are sent by a filesystem, whenever some data blocks are discarded. However, there is no way to know the number of notifications in the latter case. Use `notify_free' to account the number of pages freed by zram_bio_discard() and zram_slot_free_notify(). Depending on usage scenario `notify_free' represents: a) the number of pages freed because of slot free notifications, which is equal to the number of swap_slot_free_notify() calls, so there is no behaviour change b) the number of pages freed because of REQ_DISCARD notifications Signed-off-by: Sergey Senozhatsky Acked-by: Minchan Kim Acked-by: Jerome Marchand Cc: Nitin Gupta Cc: Chao Yu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds (cherry picked from commit 015254daf1753003c19c46b90ee85a963260d270) Signed-off-by: Alex Shi Conflicts: Documentation/ABI/testing/sysfs-block-zram --- diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram index 31db44f01936..0c7f4f91c6b5 100644 --- a/Documentation/ABI/testing/sysfs-block-zram +++ b/Documentation/ABI/testing/sysfs-block-zram @@ -76,11 +76,14 @@ What: /sys/block/zram/notify_free Date: August 2010 Contact: Nitin Gupta Description: - The notify_free file is read-only and specifies the number of - swap slot free notifications received by this device. These - notifications are send to a swap block device when a swap slot - is freed. This statistic is applicable only when this disk is - being used as a swap disk. + The notify_free file is read-only. Depending on device usage + scenario it may account a) the number of pages freed because + of swap slot free notifications or b) the number of pages freed + because of REQ_DISCARD requests sent by bio. The former ones + are sent to a swap block device when a swap slot is freed, which + implies that this disk is being used as a swap disk. The latter + ones are sent by filesystem mounted with discard option, + whenever some data blocks are getting discarded. What: /sys/block/zram/discard Date: August 2010 diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 204b7fa9d78e..3503019a9672 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -697,6 +697,7 @@ static void zram_bio_discard(struct zram *zram, u32 index, bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); + atomic64_inc(&zram->stats.notify_free); index++; n -= PAGE_SIZE; }